<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title><style>
        .box{
            width: 200px;
            height: 200px;
            border: 1px solid red;
        }
    </style>
</head>
<body>
      <div class="box"style='background-color:red;'>
        123456
        <ul>
            <li>1</li>
            <li>2</li>
            <li>3</li>
        </ul>
      </div>
</body>
   <script>
    obox = document.querySelector('.box')
    console.log(obox.style)
    console.log(obox.style[0])
    console.log(getComputedStyle(obox))
    console.log(getComputedStyle(obox).fontSize)

    console.log(getComputedStyle(obox).background)

    
   </script>
</html>